A balun is a well known device having a single ended (unbalanced) side and a balanced side. The function of a balun is to provide voltages at first and second ports of its balanced side which are substantially equal in amplitude and substantially 180.degree. out of phase with respect to each other. In other words, the balun is to provide equal and opposite voltages to a balanced load with respect to ground.
When utilizing a balun, the balun must be impedance matched with the rest of the system in order to minimize losses and distortion and maximize bandwidth, for example, in balanced amplifier applications. In trying to match the balun with the system, the prior art utilizes traditional measurements on the single ended side of the balun. For example, in measuring the frequency response of a balun, first and second baluns are serially coupled wherein their balanced sides are interconnected. A signal is applied at the single ended side of the first balun, while the signal appearing at the single ended side of the second balun is observed. From this measurement, one can obtain the bandwidth, insertion loss and return loss for each balun (assuming that each balun is substantially identical). However, these measurements do not convey any information about the amplitude and phase relationships appearing at the balanced side of the balun.
Hence, there exists a need for recognizing that the amplitude and phase of the voltage signals appearing at the balanced side of a balun may degrade with frequency and for further providing a circuit and method for providing compensation for such amplitude and phase degradation.